A small project like that is really not difficult as a DIY if you plan properly. The key to any and all concrete placement is reinforcement and control joints.

If concrete moves (and it almost always will) it will crack. My understanding is that you either need to keep it from moving or control where it cracks. The first part is almost impossible, so control and expansion joints need to be installed. On the floors I just poured, the installer placed 1/2" foam around the perimeter for expansion and cut control joints in with a diamond blade saw. My last house was done the same way, and it's amazing that the floor cracked within almost every saw cut. You could see it if you looked into the saw cut. (I never did get around to filling the saw cuts with silicone - hopefully I do on this one.)